This project extends and expands on an initial investigation based on Medicaid paid claims files to (1) confirm on an expanded and more complete data set the male/female differential in HIV-related health services utilization; (2) measure the impact of AZT usage on average monthly payments over time; (3) investigate the apparent underutilization of health services by 20% of persons with HIV related causes of death; (4) explore the health services utilization by HIV-infected mother-child dyads; (5) examine possible six month cycles of health services utilization; (6) investigate possible health services utilization and cost differentials for HIV infected individuals, with and without substance abuse problems. We will also validate our approach to differentiating between HIV- related and unrelated health care by examining the medical records of 30 HIV-infected individuals. We will also request 100 hospital discharge abstracts form a sample of Detroit area hospitals, to confirm with greater diagnostic detail the judgment made concerning the initiation of HIV-related health services utilization.